Immunology Flashcards
(232 cards)
what are the consequences of immune recognition
intended destruction of the antigen and incidental tissue damage
what are hypersensitivity reactions
immune response that results in bystander damage to the self
briefly describe the 4 types of hypersensitivity reaction
I: immediate killing
II: Direct cell killing
III: Immune complex mediated
IV: delayed type hypersensitivity
describe what type 1 reactions are characterised by (immediate killing)
characterised by greatly enhanced sensitivity to normally innocuous substances, leading to physiological responses and tissue damage
what do type I reaction leads to
allergic diseases and reaction, signs and symptoms
define an allergy in immunological terms
IgE-mediated antibody response to external antigen (allergen)
what is happening to the prevalence of allergies
increasing
what are common allergens that trigger allergic reactions
(most soluble proteins that function as enzymes)- dust mites, protein in animal saliva, pollen, food, drugs, bee and wasp venom
are all adverse reactions allergic
no
what is the hygiene hypothesis
changes in microbial stimuli influence the maturation of the immune response- results in increased predisposition to allergic conditions during childhood
why is allergy prevalence increasing and associated with western countries
the hygiene hypothesis- improved sanitation and decreased incidence of infectious disease
what enhances the immune system
exposure to bacteria or viruses e.g. infections contracted from siblings or peers at daycare centres
what happens to CD4 T lymphocytes at birth
primed to develop into TH2 cells
what does exposure to antigens do to the development of TH2 cells
dampens it, creating bias towards TH1 response- TH1 differentiation stimuli, limiting allergies and asthma
what are the generic features of type 1 allergic disease
occurs quickly after exposure to allergen (1-2 hours), reactions influenced by site of contact
what are the specific features of type 1 allergic disease
asthma, urticaria (hives), angioedema (swelling), allergic rhinitis (hayfever), allergic conjunctivitis, diarrhoea and vomiting, anaphylaxis
what immune cells are involved in allergic disease
b lymphocytes, t lymphocytes, mast cells (eosinophils and basophils)
how are B lymphocytes involved in allergic reactions
recognise antigen, produce antigen-specific IgE antibodies
how are T lymphocytes involved in allergic reactions
TH2 cells provide help for B lymphocytes to make IgE antibody
how are mast cells involved in allergic reactions
inflammatory cells that release vasoactive substances
what results in the differentiation of CD4 T cells into effector TH2 cytokine-producing cells
stimulation of allergen-specific T cells by allergen-derived peptides, presented by dendritic cells in the context of class II MHC molecules
what regulate the immune response
interleukins IL-4, IL-13, IL-5 produced by TH2 cells
how do interleukins regulate the allergic response (3)
regulate the synthesis of IgE by B cells, stimulate differentiation and migration of eosinophils from the bone marrow into the blood, helping to activate mast cells and eosinophils at sites of allergen exposure
how is the secretions of B cells altered by TH2
initially secrete IgM but initiated by TH2 cells to produce IgE